[Exim] Alias (invisible translation)

Hello all,

I'm using Exim (4.14) together with Cyrus Imap (2.1) and Sieve (for
vacation and filtering). Most functionality is in place, however, I have
a problem with aliases and vacation messages:

When I send an email directly to a user a sieve script is triggered
correctly and a vacation message is sent as an reply.

When I send an email to an alias the sieve script isn't triggered and no
vacation reply is sent. the recipient receives the message just fine.

I guess this has something to do with the header, could anyone elaborate
a bit on this?

The problem could be solved by a more advanced sieve script but I do not
want to do this. It must be easy for users to turn on the vacation
feature, and hence I have chosen SmartSieve - a web interface for
creating sieve scripts. Also, users may not know all aliases that point
to them, so even a more advanced script might not guarantee a vacation
reply.

Is it possible to configure exim so that an alias translation isn't
visible to the recipient (imap/sieve)?

Below is attached some of /etc/exim.conf,

Thanks in advance,

Michael

drop_cr
qualify_domain = skalform.dk

begin routers

system_aliases:
driver = redirect
allow_fail
allow_defer
data = ${lookup{$local_part}lsearch{/etc/aliases}}
file_transport = address_file
pipe_transport = address_pipe


local_user_cyrus:
driver = accept
transport = local_delivery_cyrus_lmtp

begin transports

local_delivery_cyrus_lmtp:
driver = lmtp
command = /usr/libexec/cyrus/deliver -l -q
batch_max = 35
user = cyrus

begin rewrite

*@*.somedomain.com $1@???